Integrated Excel workbook for Wood Structure Design 3

[AELLC]

I have seen many Excel worksheets that do individual design tasks and I wanted to start a discussion regarding integrating all that into one large workbook to streamline the entire design process.

I have my own workbook that I have improved over about 18 years and wanted to share ideas, etc.

It is Excel 2010 but can be saved as 2003-2007 with minor loss of functionality. It has no macros, UDF, or VBA etc., just basic Excel formulas, and nothing iterative.

I don't want to get into VBA discussions because not everyone is familiar with that.

 

[RFreund]

Sorry to throw you guys off here but....
when you say "embed the beamanal program into your workbooks" what do you mean by this or better yet how do you do this?
In essence the idea is to send each beam input into the beamanal program but there is only one instance of the program (not one instance for each beam), correct?

EIT

http://www.HowToEngineer.com

 

[AELLC]

RF,
No problem - I wanted this thread to be a discussion.

YES - to keep the Excel file size from getting too large and slowing down the re-calc time (my Excel for instance has 36 girder truss labels and 116 beam/header/rafter/joist labels)

Read the "user's manual" of my post 20 MAR 14 18:18

Here is the latest Excel example of all this -

 

[jeffhed]

AELLC,
Our footing program does do it automatically. We print the worst case continuous footing calculation from our spreadsheet and then just change to a second tab that is labeled max point load and print it. It gives a value for an interior footing with no thickened slab and a value for an exterior footing with a thickened slab. How do you take the eccentric loading of a footing at the corner of the slab into account? We have always assumed that with the load at the corner, there would be eccentric loading without a spot footing.

RFreund,
You can insert the beamanal spreadsheet into your spreadsheet and then link the cells. However, originally you would need a separate beamanal sheets for each beam you are calculating. AELLC has streamlined this method I think by using the embedded beamanal spreadsheet to calculate the loads and then "freezing" them by entering the numbers and overwriting the formulas in those cells. It has been a few days since I looked at his sheet he posted, so he may need to correct me.

 

[AELLC]

Here is the version without all the reaction numbers overriding the cell formulas in GT and BH tabs (but this version does not have the latest DATA tab improvements)

I will post a clean more updated version in a few days.

 

[AELLC]

jeff-

Wall footing @ corner w/ conc load -I don't account for the eccentricity. I need to study if this is a significant problem.

"AELLC has streamlined this method I think by using the embedded beamanal spreadsheet to calculate the loads and then "freezing" them by entering the numbers and overwriting the formulas in those cells. It has been a few days since I looked at his sheet he posted, so he may need to correct me. "


Correct. The modified Beamanal is actually the CSB tab in my workbook.

 

[AELLC]

"Our footing program does do it automatically. We print the worst case continuous footing calculation from our spreadsheet and then just change to a second tab that is labeled max point load and print it. It gives a value for an interior footing with no thickened slab and a value for an exterior footing with a thickened slab."

I still can't visualize that - can you send a pdf example? Or better yet, a values-only version of the whole excel worksheet?

 

[jeffhed]

A values only version is attached.

 

[AELLC]

jeff - thanks

I think got it -

1) Excel takes maximum plf wall footing (such as from roof trusses bearing on wall) - particular to the project - that value was linked from another sheet?

2) Excel computes and displays maximum allowed conc load that can be added a) to int ftg b) to ext ftg
- based on what is the "left over capacity" after the wall plf is deducted.

 

[jeffhed]

AELLC,
Yes. The loads come from the continuous footing calculations spreadsheet. You enter all the information for the continuous footing and then print. There is a second tab that says maximum footing load and all uniform loads, footing size and reinforcing are taken from the cover sheet where the information is entered.

 

[AELLC]

OK, good thing I have time for all this. I have had very little real billable work for 2 weeks now.

I have 3 projects that are having truss problems, as you see I am starting a lot of threads in Structural Engineering - Other Topics, and in TRUSS Engineering, blah blah - but all that seems to be cleared up now.

Anyways, how I set up the footing design here may be quite unconventional, but I am going to welcome criticism.
It is very related to the OP because it involves a lot of linked cells from sheet to sheet, and all data entry has ben minimized.

Any one else in the "loft", let's hear from you, too.

 

[AELLC]

"Wall footing @ corner w/ conc load -I don't account for the eccentricity. I need to study if this is a significant problem."



For 16" wide footing and allow=2000 psf soil brg, I get 5485#, is that close to what you get?

 

[jeffhed]

With my method?

 

[AELLC]

I meant with the post load only, no continuous bearing wall load.

I am not very confident with this particular calc. There are too many assumptions. This calc is "gray", not black and white.

 

[AELLC]

Yikes it is 11:20, I am getting some zzzz's

 

[jeffhed]

I guess I'm not sure which method you used. If I use your method just based on a 45 degree angle and an 18" thick slab and footing I get 4.44 sq. ft. which gives me a load on the soil of 8880 lbs. You'll have to show me your area you came up with. I have attached a drawing showing the area I came up with using your method. It also shows what I was talking about before about corner footings being eccentrically loaded. It may not be a big deal, but if you are trying to use the "legs" of the footing going each way there will be an eccentricity. If you were standing on a piece of plywood in an L shape on water and you stood on the corner, the plywood would want to tip at the ends of the legs. It may not add up to much, maybe the slab restrains/removes the eccentricity?

 

[AELLC]

The continuation of the reinforced stem adds greatly to removing the eccentricity, but it is a very gray judgment call.

 

[AELLC]

See attached

 

[jeffhed]

I agree with the max point load of 8880 lbs being unconservative, thats why I usually use spot footings at corners if the loads are very high. Did you calculate the bearing pressure with the eccentricity? I didn't go into it that far for the same reasons as you. The slab is doing something and the wall load along the legs of the L shaped footing will help remove the eccentricity as well. There is so much going on there that getting a calculation to model what is really happening is difficult to envision. Maybe I am overthinking it. For corner footings I usually see how much a spot footing would be the same width of the continuous footing, only square. So for a 16" wide continuous footing, I would use a 16" square footing and considering the wall load I would determine how much additional point load I could take, probably pretty overconservative, but there are not eccentricities and I have never had someone complain about a few spot footings here or there in the perimeter continuous footing. So did you ran calculations with the eccentric loading to come up with your max load of 5485 lbs? That appears to be in line because a 16"x16" square spot footing with no loading would give me 3556 lbs allowable point load.

 

[AELLC]

Thanks, I am going to go with 5485 because 3556 looks too conservative.

I need to gauge how much I can get away with (value engineering)

 

[jeffhed]

I guess you could calculate the flexural strength of the thickened slab, but how would you determine if it was enough to remove the eccentricity? I calculate a 10x10 concrete beam with one continuous #4 bar has an allowable moment of 4341 lb-ft (LRFD level). Dividing that by 1.6 to conservatively reduce that to ASD level gets us to 2894 lb-ft. Dividing our footing by 1'-8" (the moment arm from our l-shaped footing drawing) gives us a point load of 1733 lbs at the end. If you multiply that by two since you will have a thickened slab coming from each direction, that gives us a load of 3466 lbs. That isn't including deflection, so maybe that gets reduced a little. But it could definitely help in increasing the allowable load on your corner footing by reducing or removing the eccentricity.